Heating apparatus



Ailg. 1 8, 1936. T. w. MUNFORD HEATING APPARATUS Filed Dec. 30 1955INVENTOI? Z'W/Wuhforc/ A TTORNE Y Patented Aug. 18, 1936 Iss triesSurface Combustion Corporation,

Toledo,

Ohio, a corporation of New York Application December 30, 1935, SerialNo. 56,622

10 Claims.

The invention relates to fuel fired radiator tubes and has for itsobject to provide a radiator tube of such'form that it may be uniformlyheated to such high temperatures that it shall have special utility as aheat radiating element in furnace chambers and the like where hightemperature heating elements are required. Other objects will more fullyappear hereinafter.

The various features of novelty and invention will be fully described inconnection with the accompanying drawing forming part of thisspecification and wherein',-

Fig. 1 shows the improved heating apparatus partly in elevation andpartly in section and as extending through the wall of a furnace chamberwhich is to be heated;

Fig. 2 is a cross sectional view on line 22 of Fig. 1; and

Figs. 3 and 4 are section views of parts shown in elevation in Fig. 1.

The heat radiator tube is generally indicated at It and is shown as ofhair-pin type with its intake and exhaust ends extending through a wallll of a furnace chamber which is to be heated. Fuel is delivered to theintake end of the tube It by means generally indicated atl2, and air forsupporting combustion of the fuel is induced to enter said end by adraft producing means generally indicated at l3 at the exhaust end ofthe tube.

The means l2 for delivering fuel to the radiator tube includes a fueldelivery tube It to which fuel gas is supplied by a pressure gas supplypipe l5 having a regulating valve IS. The fuel tube It is shown asextending a substantial distance into the inlet end of the radiator tubel0 primarily to compensate for the thickness of the furnace wall II. Thefuel tube I4 is of relatively large cross sectional area without anyconstriction at its discharge end such as would tend to prevent the fuelstream from maintaining its integrity for a substantial distance afterdischarge from the tube.

It is essential to the successful firing of the radiator tube that thecombustion supporting air be induced to enter the intake end of the tubeby draft producing means at the exhaust end of the tube, and said meanspreferably takes the form of jet entraining apparatus consisting of ajet orifice nozzle is positioned to discharge into an eductor tube [9which forms in eifect an extension of the radiator tube. The fluidpressure supply pipe for the nozzle is indicated at 20 and is providedwith a regulating valve 2| to permit the entraining eifectto be adjustedas desired.

Inasmuch as the strong draft through the radiator tube tends to pull theflame away from the fuel tube and thus causes it to go out, means areprovided for constantly insuring ignition of the air and fuel where theyinitially intermix in combustible proportions and the means hereindisclosed for that purpose will now be described. Surrounding the fueltube It in spaced relation is a tube 22 to which preformed combustiblemixture under pressure is supplied by a supply pipe 23 having regulatingvalve 24. In the tube 22 near its outlet end is a ring 25 through whichthe fuel .tube 14 passes and which is provided with a plurality ofrelatively small passages through which the mixture supplied to theouter tube 22 must flow to pass from the latter. The fuel tube l4extends beyond the tube 22 and the space between the two tubes at thedischarge side of the ring 25 constitutes an annular combustion chamber26 for the combustible mixture flowing through said ring. The outer endsof the tubes Hi and 22, therefore, become highly heated and along withthe high temperature gases issuing from said chamber constantly insureignition of the fuel issuing from the inner tube M.

In order to permit the burning of a greater volume of fuel in theradiator tube I0 than could possibly be burned if the tube were ofuniform cross sectional area through its length, the

present invention provides a radiator tube of special form as will nowbe described. Where the tube passes through the furnace wall II and fora substantial distance into the furnace chamber, it is circular asindicated at 28. This ci'rcular part 28 is followed by part 29 whosecross sectional area is somewhat greater than the preceding section andwhich is oblong in cross section and of greater length than thepreceding part. This difference in contour between the two parts 28 and29 materially speeds up interunixing of the air and fuel 'in thecomposite stream as it flows from the part 28 to the part 29 with theresult that combustion is correspondingly accelerated but not to suchdegree as to cause objectionable spot heating. The increased liberationof heat is compensated for by the greater heat absorbing surface of thepart 29 and consequently the tube does not become overheated. Sincecombustion tends to decelerate due to the air and fuel becoming dilutedwith products of combustion, the present invention provides for repeatedacceleration of combustion by following the expanded part 29 with parts30-35 of which parts 30, 32 and 34 are preferably circular and of thesame cross section area as the first part 28 whereas the parts 33 and 35are preferably of the same cross sectional contour andarea as the part29. This periodic expansion and contraction of the gases promotesintermixing of the gases in the stream as will now be readily understoodwith the result that combustion of residual fuel will be accelerated andcombustion completed before the gases reach the exhaust end of the tube.The last portion 36 of the tube where it passes through the furnace wallII is preferably circular in cross section and of the same diameter asthe first portion 28. It will be readily appreciated that in a hair-pintube the bend 3| is also an important factor in materially stirring upthe gases as they flow therethrough.

The first expanded part or section 29 is of relatively greaterimportance than the other expanded sections 33 and 35, it being noted inthis connection that the last named sections are severally shorter thanthe first section 29. The short width or minor axis of the severalexpanded sections is preferably the same as the diameter of thepreceding round section as is clearly shown in Fig. 2 whereby the gasesin flowing from the round into the, oblong section of the tube expandonly in two opposite directions, it having been found that theturbulence or stirring produced in the gases by this arrangement givesthe best results.

The advantages of a radiator tube constructed in accordance with thepresent invention may be stated as follows:

(1) Owing to the greater internal volume than a circular tube of equallength, a longer time is expansion away from the outer core of thestream, and this outward movement induces a turbulent area at the corethus promoting thorough mixing of the air and fuel in the process ofburning. Owing to the tubeform, ample space is provided for flow throughthe tube on either side of the turbulent area without excessive frictionlosses.

(3) In spite of the fact that turbulence is produced in successive partsof the tube, no localized heating is produced since the turbulent areasare separated from the tube walls by those portions of the total gasstream flowing along the walls in substantially stream line flow underthe influence of the draft source at the exhaust end of the tube.

(4) By utilizing a radiator tube of the type herein disclosed, theamount of fuel that can be burned in the tube is greatly in excess ofwhat could be burned if the tube were of uniform cross sectional areathrough its length, and consequently, the utility of the tube iscorrespondingly increased due to the high temperature to which it can beheated.

What I claim is:

1. In combination, a radiator tube, and means for burning fuel thereincomprising a suction producing means coupled to the exhaust end of thetube for inducing combustion supporting air to enter the intake end ofthe tube, means at the air intake end of the tube for discharging fluidfuel thereinto, and said tube having an oblong section preceded andfollowed by a circular section whose diameter is substantially the sameas the minor axis of the oblong section. I

2. In combination, a radiator tube, and means for burning fuel thereincomprising a suction producing means coupled to the exhaust end of thetube for inducing combustion supporting air to enter the intake end ofthe tube, means at the air intake end of the tube for discharging fluidfuel thereinto, and said tube being of hair-pin type and having betweenits bend and its intake end an oblong section preceded and followed by acircular section whose diameter is substantially the same as the minoraxis of the oblong section.

3. In combination, a radiator tube, and means for burning fuel thereincomprising a suction producing means coupled to the exhaust end of thetube for inducing combustion supporting air to enter the intake end ofthe tube, means at the air intake end of the tube for discharging fluidfuel thereinto, and said tube being of hair-pin type and having in eachof its legs an oblong section preceded and followed by a circularsection whose diameter is substantially the same as the 20 minor axis ofthe oblong section.

4. In combination, a radiator tube, and means for burning fuel thereincomprising a suction producing means coupled to the exhaust end of thetube for inducing combustion supporting air to enter the intake end ofthe tube, means at the air intake end of the tube for discharging fluidfuel thereinto, and said tube being of hair-pin type and having in eachof its legs an oblong section preceded and followed by a circularsection whose diameter is substantially the same as the minor axis ofthe oblong section, the oblong portion between the intake end of thetube and its bend being longer than the other oblong por- 35 tion.

5. In combination, a radiator tube, and means tube for a portion of itslength remote from the last named means being of greater cross sectionalarea than in the preceding portion of the tube.

6. In combination, a radiator tube, and means for burning fuel thereincomprising power-operated suction producing means coupled to the exhaustend of the tube for inducing combustion supporting air to enter theintake end of the tube, means at the air intake end of the tube fordischarging unignited fuel therelnto, and said tube comprising analternate succession of restricted and expanded sections.

7. A combustion chamber consisting of a radiator tube having asubstantial portion of its length between its ends of greater crosssectional area than the next preceding and following portions and thedistance between the intake end of the tube and the point where saidportion begins being many times less than the distance between the pointwhere said portion ends and the exhaust end of the tube, said enlargedportion being oblong in cross section and the next adjacent portionbeing circular and the diameter of the circular portion beingsubstantially the same as the short axis of the oblong portion.

8. A combustion chamber consisting of a radiator tube having asubstantial portion of its length between its ends of greater crosssectional area than the next preceding and following portions and thedistance between the intake end of the tube and the point where saidportion begins being many times less than the distance between the pointwhere said portion ends and the exhaust end ot the tube, and said theends of the last mentioned dist are x u: least one additional enlargedportion of shorter length then the first mentioned portion.

9. A combustion chamber oonsistmg 0: e rm?- ator tube of hale-pm type habetween its bend and its intake end a portion which is oblong in crosssection and which is preceded and. followed by e circular portion whosediameter is substantially the same as the minor axis of the oblongportion.

10. In combination, a. combustion ber consisting of a, radiator tube been sueoewon of circular and oblong sections, means for flowing,unignitecl fuel into the intake end of the tube, means for producing astrong draft vthroturh the tube whereby to cause air to stream into theintake end of the tube and how towards the exhaust end thereof tosupport combustion of the fuel as it flows through the tube, and meansat the intake end of the tube for insuring that ignition of combustiblemixture resulting from tntermixlng of the flowing air and fuel shell on10 our es and when said mixture is initially formed.

